Performing an Action on Certain Media Streams in a Multimedia Communications Network

ABSTRACT

The invention proposes controlling a media session involving a plurality of media streams within a communications network, wherein the communications network comprises a media resource node ( 106 ) and a media control node controlling ( 102 ) the media resource node, wherein the media control node performs a method of determining that selected media streams out of the plurality of media streams are associated to each other in a media session, transmitting to the media resource node ( 106 ) an instruction to group the selected media streams of the media session, and transmitting to the media resource node ( 106 ) an instruction to prepare for performing an action with respect to the selected media streams. The invention further proposes a corresponding method to be performed in a media resource node ( 106 ), corresponding nodes ( 102, 106 ) and corresponding computer programs.

TECHNICAL FIELD

The present invention relates to media handling in multimediacommunications networks, and specifically relates to an interactioninvolving a session control protocol and a media gateway protocol.

BACKGROUND

Modern communication networks often show a “decomposed” or layeredarchitecture, in which the call and session control layer and the mediaplane layer are handled by different instances that are typicallyrealized as separated physical nodes. Typically the nodes of the calland session control layer are referred to as media gateway controllersand the nodes of the media plane layer are referred to as mediagateways.

A protocol widely used in the control layer for controlling sessionsconsisting of one or several media streams is the Session InitiationProtocol SIP being specified in the Internet Engineering Task Forcedocument “IETF RFC 3262, Session Initiation Protocol” in the followingbeing referred to as RFC 3262.

A further protocol defined by the IETF, the Session Description ProtocolSDP specified in the IETF document RFC 4566, is used in a variety ofnetworks and communications systems for describing multimedia sessions,e.g. for the purpose of session announcement, session invitation andother forms of multimedia session initiation. Examples of such networksare the IP Multimedia Subsystem—IMS—and the Multimedia TelephonyService—MMTel—. The SDP is thereby used in combination with the SIP in away that SDP messages or packages are embedded into SIP.

Since its origins, SDP has evolved with new capabilities to respond tothe needs of new applications, as corresponds to a constantly growinguse of the protocol. A capability to group different media has beenspecified for different applications in various IETF documents. By meansof media grouping in SDP, a particular relationship between two or moremedia streams can be indicated.

The framework for grouping of media is specified in the IETF documentRFC 5888 that also specifies specific applications for the use of thiscapability, and further in the IETF document RFC 4588 titled “TheSession Description Protocol (SDP) Grouping Framework”.

According to the RFC 5888, a plurality of media streams may be groupedtogether. Depending on the type (semantics) of the grouping, certainactions which would otherwise be handled individually per stream may berequired on the complete group of streams. In the following, someexamples are given:

An announcement (video and/or audio) shall be sent simultaneously to twogrouped (video and/or audio) media streams

When several grouped media streams traverse a node, for example a mediamixer, the input and output stream end points of the node may have to beconnected in such a way that several grouped media streams at one endpoint are mapped into one single media stream at the other end point.

Statistics: for some streams that are grouped together according to the“BUNDLE” semantics it may be required to collect statistics (e.g.received octets) for all of them together, rather than for each of themindividually.

Events: for some streams that are grouped together (e.g. using so-calledflow Identification, FID, semantics), it may be desired to arm thedetection of incoming digits (eDTMF or telephony events) simultaneouslyin all grouped streams.

One example for a protocol to be used between the control nodes and themedia plane nodes is specified in ITU-T Recommendation H.248.1, titledGateway Control Protocol (current Version 3), in the following alsobeing referred to as media gateway control protocol or simply as H.248.

In a decomposed gateway, the actions above are controlled by MGCinstructions e.g. instructions according to the H.248 protocol.

Patent application PCT/EP2011/061462 of the same applicant discloses amethod to initiate a media session within a communications networkinvolving a plurality of media streams, wherein the communicationsnetwork comprises a plurality of media control nodes (media gatewaycontrollers) and a plurality media resource nodes (media gateways) beingcontrolled by each one of the media control nodes. Thereto, a certainmedia control nodes instructs a media resource node being controlled bythat media control nodes to associate or group two or more of the mediastreams, e.g. a subset of all streams handled by a termination of themedia resource node.

This allows a control layer node (a media gateway controller or MRFC) toinstruct a node of the media layer (a media gateway or a MRFP), by meansof a corresponding session description, to create appropriate mediastream sinks and sources (such logical entities also being referred toas terminations within the H.248 terminology) for handling multiplemedia streams and grouping corresponding two or more of these mediastreams. Thus controlling a grouping (or association) of different mediastreams of multimedia applications like videoconference and so-calledtelepresence might be accomplished involving a plurality of mediagateway controllers and a corresponding plurality of media gateways.

Example for use cases are:

-   -   Synchronized play out of a video and an audio stream        (lip-synchonization, LS) or of an audio stream and its        simultaneous translation (LS semantics are defined in RFC 5888).    -   Use of a redundancy media stream for error protection purposes        (the original stream and the redundancy stream may use the FID        media grouping semantics, as defined in RFC 4888).    -   Use of one or more Forward Error Correction streams (the        original stream and the forward error correction stream(s) may        use the FEC media grouping semantics, as defined in RFC 4756).    -   The FID semantics may also be used to group multiple audio        streams which use different audio codecs. Only one of them is        used at a time. The streams with the ones not used remain silent        during that time. In another use of the FID semantics, if two of        these streams use the same audio codec, a replica of the media        is sent is sent in the stream with the same codec (as specified        in RFC 5888).    -   Two or more media streams may use the same source and        destination IP addresses and ports. These media grouping        semantics is called BUNDLE and is e.g. being specified in the        draft-ietf-mmusic-sdp-bundle-negotiation IETF draft.    -   Multiple video streams with the same content, but with different        resolutions may be grouped together with a simulcast media        grouping.

However, not always all streams associated to one termination within thegateway are to be grouped. There may be situations wherein only a subsetof such media streams shall be grouped. However, current protocols forthe control of media gateways do not allow commanding certain actions,such as those previously listed regarding playout of signals, detectionof events, collection of statistics, on a stream group when such partialgrouping exists. Furthermore, for some grouping semantics therealization of a signal, event or statistics in the group of streams maynot be identical to the realization of such signal, event or statisticin every individual stream of the group. In such case, current protocolsalso do not allow commanding such signal, event or statistics in thegroup of streams. Furthermore, current protocols do not allow commandingthe establishment of certain forms of connectivity if the same groupingis not defined at the other side of the connection, i.e. in the othertermination.

Specifically, H.248 does not allow applying a signal simultaneously toseveral media streams in a termination unless it is applied to all mediastreams of the termination. Further, H.248 does not allow arming anevent simultaneously in several streams in a termination unless it isarmed in all media streams of the termination. There is further nomechanism to combine (aggregate) statistics on several streams in atermination (unless it is done on all streams of the termination).

There is no mechanism to connect both-way or one-way two or more streamsat one side with one single stream at the other side (unless the nodeapplies multiplexing). The mechanism used in H.248 to specify theconnectivity between the stream end points is the topology. It may benoticed that H.248 supports the mixer case where several stream endpoints are connected to each other, normally with both-way topology, butin that case every end point handles the same number of streams.

SUMMARY

It is an object of the present invention to improve a grouping of aplurality of media streams in a decomposed multimedia network comprisinga media control layer being separated from a media plane (also beingreferred to as bearer or connectivity) layer.

According to an embodiment, a media session within a communicationsnetwork is initiated and/or controlled involving a plurality of mediastreams, wherein the communications network comprises a plurality ofmedia control nodes e.g. so-called media gateway controllers, MGC, and aplurality media resource nodes so-called media gateways, MG, beingcontrolled by each one of the media control nodes, wherein one of themedia control nodes instructs a media resource node being controlled bythat media control nodes to associate or group two or more of the mediastreams constituting a subset of all streams handled by a termination ofthe media resource node.

In an embodiment, the media control node determines that selected mediastreams out of the plurality of media streams are associated to eachother in a media session, and transmits an instruction to group theselected media streams of the media session.

In a further embodiment, the media control node further transmits aninstruction to prepare for performing an action with respect to theselected media streams.

In a further embodiment, the media control node transmits an instructionto perform the action with respect the selected media streams to themedia resource node. Transmission may be performed together orsubsequently with the media stream grouping instruction (i.e. during aninitialization stage to setup termination/media streams in the mediaresource node) or during runtime (i.e. a certain time later after theinitialization phase has been accomplished).

In a further embodiment, the instruction to group the selected mediastreams comprises a list of media stream identifiers, e.g. integernumbers, created at the media resource node.

In a further embodiment the instruction to prepare for performing anaction with respect to the selected media streams comprises a mediastream identifier representing the group of selected media streams.

In an embodiment, a stream representative is specified, that acts as avirtual stream in the sense that if the media gateway controllerinstructs the media gateway to perform an action with respect toselected media streams; e.g.

-   -   if the MGC orders the MG to play a signal in the stream        representative, the signal will be played in all the grouped        streams.    -   if the MGC orders the MG to arm an event on the stream        representative, the event will be armed in all the grouped        streams    -   if the MGC orders the MG to collect statistics in the stream        representative, the statistics will be collected and aggregated        in all grouped streams.    -   if the MGC orders the MG to establish a certain topology using        the stream representative, the topology will affect also all        grouped streams. However when the media in each of the grouped        streams has to traverse from/to one termination to another        termination, depending on the semantics of the grouping, not all        streams will necessary traverse. The semantics of the grouping        may imply that only one of them is chosen at a time, and this        may change dynamically without requiring MGC intervention.

According to embodiments of the invention, telecommunicationsapplications like video conference, telepresence systems, are enabled toperform a grouping in a layered architecture having separate mediacontrol and media connectivity layers, e.g. by applying a mapping ofinformation elements of the Session Description Protocol into asmentioned in the introductory section.

In a further embodiment, in a videoconference scenario, a grouping isperformed comprising a high quality video and a standard quality videoof the same content to be simultaneously transmitted to the sameparticipant e.g. to suit different capabilities of different receiversof this participant.

In a further embodiment, a video streaming application sends originalmedia and a replica being grouped in order to increase robustness and/orthe quality.

The present invention also concerns computer programs comprisingportions of software codes in order to implement the method as describedabove when operated by a respective processing unit of a media controlnode or a media resource node. The computer program can be stored on acomputer readable medium. The computer-readable medium can be apermanent or rewritable memory within the user device or the recipientdevice or located externally. The respective computer program can bealso transferred to the respective node for example via a cable or awireless link as a sequence of signals.

In the following, detailed embodiments of the present invention shall bedescribed in order to give the skilled person a full and completeunderstanding. However, these embodiments are illustrative and notintended to be limiting.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a principle block diagram comprising nodes being involvedin media control being performed e.g. on the basis of SDP and H.248,

FIG. 2 shows a more detailed block diagram comprising a media resourcecontroller and a media resource point involved in media stream groupingand action,

FIG. 3 shows a first flow chart for illustrating an exemplary sequenceof steps performed by a media resource controller,

FIG. 4 shows a second flow chart for illustrating an exemplary sequenceof steps performed by a media resource point,

FIG. 5a , 5.b show first exemplary instructions transmitted by a mediaresource controller, and

FIG. 6a, 6b show further exemplary instructions transmitted by a mediaresource controller.

DETAILED DESCRIPTION

FIG. 1 shows a principle block diagram of a part of a multimediacommunications network, by way of example comprising a first mediaresource controller (or media gateway controller, MGC) 102, a secondmedia resource controller 104, a first resource point (or media gateway,MG) 106 and a second resource point 108. By way of example, firstresource point or MG 106 comprises a first termination T1, and secondresource point or MG 108 comprises a further termination T11 that arecoupled to each other to form a communication channel 110 within themedia layer. By way of example, first media resource controller 102 andsecond media resource controller 104 communicate by means ofabove-mentioned SIP protocol and first (second) media resourcecontroller 102 (104) communicates with first (second) resource point 106(108) by means of a protocol according to H.248 enhanced according toembodiments to the invention (also being referred to as enhanced H.248in the following).

Each termination T1 and T11 may be a media stream sink and/or mediastream source that might each be characterized by address(es) (e.g. anIP address), port number(s) and type(s) of media. By way of example, thefirst media resource controller 102 communicates with the first resourcepoint 106 by sending a command (e.g. “add”) to instruct a creation ofthe first termination T1 for handling a plurality of (e.g. three) mediastreams and receiving a reply associated to the command (e.g. “addreply”). The command may comprise an order to group all the mediastreams or a subset of the media streams (e.g. two of three mediastreams). This command might be provided by means of the H.248 protocol.

Additionally, the first media resource controller 102 may send acorresponding offer (e.g. “SDP offer”) comprising a correspondingsession description comprising a description of the plurality of mediaand the grouping information to the second media resource controller104. The second media resource controller 104 might accept the offer bya reply (e.g. “SDP answer”). Corresponding to the communication betweenthe first media resource controller 102 and the first resource point106, the second media resource controller 104 generates a command (e.g.“add”) to creating the further first termination T11 of the second MG108 on the basis of the SDP offer received from the first media resourcecontroller 102.

The first media resource controller 102 may comprise a first H.248interface (circuit) 1021 for providing an H.248 interface to the firstmedia resource point 106 and a first SDP interface (circuit) 1023 forproviding and SDP interface to the second media resource controller 104.Similarly, the second resource controller 104 comprises correspondingsecond H.248 and SDP interfaces 1041 and 1041.

In the example of FIG. 1 the second resource controller 104 may furthercomprise a translation or mapping unit 1042 for performing a mapping ofthe session description carried by the offer received from anotherresource controller (e.g. the first media resource controller 102). Themapping unit detects the plurality of media and the grouping informationfrom the offer, determines that these (or some of these) media areassociated to the corresponding termination T11 and generates aninstruction comprising a media stream description of all involved media(Stream Descriptors) and a grouping information as part of a terminationstate description associated to the second termination. Thus, accordingto the example of FIG. 1, the mapping performs a translation from themedia offer received from the first media resource controller 102 to aninstruction to be transmitted to the (second) resource point 108.

The grouping instruction each sent from the resource controller (e.g.first or second resource controller 102, 104) to the respective resourcepoint (e.g. first or second resource point 106, 108) comprises inindication to group selected media streams into a group. Further, thegrouping instruction may comprise a stream representative as discussedabove. The stream representative acts as a virtual stream specifying the(real) selected streams handled at the MG that are grouped by way of thecommands described above.

If the resource controller instructs the associated resource point toperform a certain action associated with the stream representative, theresource point will perform the commanded action simultaneously to allgrouped streams. Such action may be to play a signal in all the groupedstreams. to arm an event in all the grouped streams, to collectstatistics and aggregate them in all grouped streams, or to establish acertain topology affecting also all grouped streams.

When the media in each of the grouped streams has to traverse from/toone termination to another termination, depending on the semantics ofthe grouping, not all streams will necessary traverse. The semantics ofthe grouping may imply that only one of them is chosen at a time; thischoice may change dynamically without requiring MGC intervention.

In the following, an example is discussed with both-way or one-wayconnections between two or more streams in a first termination T1 to onestream in a second termination T2 of the first media resource point orMG 102.

Thereto, FIG. 2 illustrates an arrangement comprising the first mediaresource controller 102, the first media resource point 106, a firstparty, P1, (device) 201 and a second party, P2, (device) 204, The mediaresource controller 102 comprises the first interface 1021 and a firstprocessor 1022. The media resource controller 102 comprises the firstH.248 interface 1021 and a first processor 1022. The first mediaresource point 106 comprises a second interface H.248 interface 1061 anda second processor 1062. Further, the first media resource point 106comprises the first termination T1 and the second termination T2. Thefirst H.248 interface 1021 is coupled to the second interface H.248interface 1061. The first termination T1 is coupled to the first party201 or first remote party P1, and the second termination T2 is coupledto the second party 202 or second remote party P2.

In a two party audio call, first termination T1 shall send and receive(from/to the outside of the context) one audio stream with two payloadtypes, corresponding to two different audio codecs, e.g. Codec1 andCodec2. At a time, the audio shall be encoded either with Codec1 or withCodec2. The remote party P1 may change the codec dynamically anddeliberately. The second termination T2 may send and receive two audiostreams S1 and S2, e.g. grouped with the FID semantics according to RFC5888. First stream S1 may use Coded, and second stream S2 may useCodec2. In addition, second termination T2 may send (but in this exampledoes not receive) third stream S3 to the outside of the context, by wayof example also using Coded. Third media stream S3 by way of example mayalso be grouped with the FID semantics to S1 and S2.

Thereto, according to embodiments of the invention, a topology grouprepresentative is sent from the MGC to the MG. In this example, S1 ischosen as representative identity, as both termination T1 and T2 handleS1 media stream. This command instructs the MG to perform an action onS1 in response to a further command. Of course, the streamrepresentative may be chosen different to any of the individual streams.

The further command may comprise an indication to bidirectionallyconnect S1 to both terminations T1 and T2; i.e. the other streams S2 andS3 are terminated at Ts in this example. This command may look like (S1,T1, T2, bothway).

The expected behavior is as follows:

When first remote party P1 connected to the first terminal T1 sendsmedia encoded with Codec1, it will be forwarded to S1 and S3 in T2 tothe second party P2 connected to the second terminal T2.

When first remote party P1 sends media encoded with Codec2, it will beforwarded to S2 in T2's remote party P2.

P2 will send media encoded either with Coded or with Codec2. The mediawill be received in T2 and forwarded to T1.

It may be noted that the direction attribute shown in FIG. 2 correspondsto the end-points in the MG, e.g. to terminations T1 and T2. Thus, S3media flows only in direction from T2 to P2.

The above described topology instruction to describe the connectivityrequired above (as currently no topology mechanism for such connectivityis existing in H.248; with existing available mechanisms it is possibleto command a connection of only S1 between T1 and T2).

FIG. 3 shows an exemplary flow chart illustrating a generation of an SDPoffer with a (multimedia) session description in response to groupingcapabilities of a controlled media resource point according to FIG. 1:

The first steps S1, S2, and S3 may be performed in advance to thesequence described in the steps S4-S5.

In the first step S1, the (first) media resource controller 102 (or anyother node associated to the first media resource controller 102) mapsthe media of a multimedia session to each one H.248 stream descriptor.

In the second step S2, the media resource controller 102 determines, ifa media grouping is needed (or recommended) for this multimedia session.

If yes, in a third step S3, the media resource controller 102 generatesa grouping instruction to group a plurality of media to be handled by acertain termination of the controlled media resource point, in thefollowing being referred to as the first termination T1 of the (first)media resource point 106 (e.g. using a termination state property asdiscussed below) to be sent to the media resource point 106.

In a fourth step S4, the media resource controller 102 generates aninstruction to prepare for an action to be performed at the mediaresource point 106 on the media streams being grouped together.

Such instruction may comprise generating a group or streamrepresentative enabling the media resource controller 102 to indicate tothe media resource point 106 a virtual media stream of the terminationthat will represent the media group when requesting events, signals orstatistics applicable to all streams of the group. The associated(virtual) stream identity may be different from all stream identitiesused by any of the termination streams.

With regards to topology, the media resource controller 102 is enabledto indicate to the media resource point 106 a virtual media stream ofthe termination that will represent the media group in relation to mediastreams of other terminations as defined by the corresponding topologydescriptor. The associated stream identity may be the same as used inother terminations if a topology relationship has to be established tothose terminations.

In a fifth step S5, the first media resource controller 102 transmits tothe media resource point an instruction to perform a certain action onthe streams identified by the stream representative, e.g. to collectstatistics as discussed above.

FIG. 4 shows an exemplary flow chart illustrating action to be performedin a media resource point 106:

In a first step (of this embodiment) S11, the media resource point 106is running a session with multiple streams being grouped as commandede.g. according to FIG. 3.

In the second step (of this embodiment) S12, the media resource point106 determines, if a media representative is available.

If yes, in a third step (of this embodiment) S13, the media resourcepoint 106 determines, if an action has to be performed on the mediagroup; a corresponding instruction may have been received from the firstmedia resource controller 102.

If, yes, in a fourth step (of this embodiment) S14, the media resourcepoint 106 performs the corresponding action.

A solution proposed according to embodiments of the invention comprisesa definition of new properties on termination level. The new propertiesindicate the stream representative, if any, for each of the groupingsapplicable to the session. One proposed representative is applicable tosignals, events and statistics. A further proposed representative may beapplicable for topology. A reason to using a different stream number asrepresentative for topology is to facilitate the operations, as for thetopology representative, this stream number must exist in the othertermination in order to establish a topology relationship.

Each property may be represented as a list of strings. Each member inthe list may correspond to one member of the so-called “Group Semantics”property, listed in the same order.

Some exemplary properties definitions are listed below:

-   -   Property Name: Group Representative    -   Property ID: grouprep, (0x0002)    -   Description: This property allows the MGC to indicate to the MG        a virtual media stream of the termination that will represent        the media group when requesting events, signals or statistics        applicable to all streams of the group The defined stream        identity must not be used by any of the termination streams.    -   Type: Sub-list of integer    -   Possible values: Stream descriptor identity.    -   Default: None    -   Defined in: TerminationState    -   Characteristics: Read/Write

Stream Representative for Topology:

-   -   Property Name: Topology Group Representative    -   Property ID: groupreptop, (0x0003)    -   Description: This property allows the MGC to indicate to the MG        a virtual media stream of the termination that will represent        the media group in relation to media streams of other        terminations as defined by the Topology descriptor. The defined        stream identity must be the same as used in other terminations        if a topology relationship has to be established to those        terminations.    -   Type: Sub-list of integer    -   Possible values: Stream descriptor identity.    -   Default: None    -   Defined in: TerminationState    -   Characteristics: Read/Write

In the following an example is given for applying signals, events and/orstatistics to the group. Thereto, FIG. 5a shows an exemplary H.248command wherein a MGC groups two audio media streams with the FIDsemantics when adding a new termination. By way of example a virtualstream 8 is selected as representative. FIG. 5b shows an exemplary H.248command sent out by the MGC play the same announcement simultaneously onboth audio media streams.

In the following, an exemplary topology description for the group to beused by the MGC is shown. Thereto, FIG. 6.a shows a media descriptor forthe first termination T1, and FIG. 6.b shows a media descriptor for thesecond termination T2; the media descriptors may be included in an “Add”command.

The topology descriptor may comprise the terminations, directionalityand stream identifier:

Topology {T1, T2, BW (bothway), ST (stream)=1}

As discussed above, embodiments of the invention allow the MGC to ordera MG to act simultaneously on the media streams of a selected group ofstreams independently of any adherence to one or different terminationsof the MG. In other words, the one termination or the plurality ofterminations of the MG may terminate each one or a plurality of mediastreams belonging to the grouped media streams and may additionallyterminate one or a plurality of further media streams not being part ofthe grouped media streams.

Such action may be for example to play an audio or video announcement,to detect the reception of in-band digits (DTMF or telephony events), toorder a collection and aggregation of statistics in several streams in aMG, for example the number octets received in several streams grouped bythe BUNDLE semantics, and or to establish connectivity in a MG betweentwo or more terminations when media grouping applies only at onetermination or when different media groupings apply at differentterminations.

1-18. (canceled)
 19. A method for controlling a media session involving a plurality of media streams within a communications network; wherein the communications network comprises a media resource node and a media control node controlling the media resource node; the method comprising the media control node: determining that selected media streams out of the plurality of media streams are associated to each other in a media session; transmitting, to the media resource node, an instruction to group the selected media streams of the media session; and transmitting, to the media resource node, an instruction to prepare for performing an action with respect to the selected media streams.
 20. The method of claim 19, wherein the instruction to group the selected media streams comprises a list of media stream identifiers created at the media resource node.
 21. The method of claim 20, wherein the stream identifiers are integer numbers.
 22. The method of claim 19, wherein the instruction to prepare for performing an action with respect to the selected media streams comprises a media stream identifier representing the group of selected media streams.
 23. The method of claim 22, wherein the instruction to perform the action with respect the selected media streams comprises an indication of the media stream identifier and an indication of the action to be performed.
 24. The method of claim 19, wherein the action to be performed comprises at least one of: an instruction to play a signal in the media streams of the group; an instruction to play a signal in selected media streams; an instruction to arm an event in the media streams of the group; an instruction to collect statistics in the media streams; and an instruction to collect statistics in the media streams and to aggregate the statistics.
 25. The method claim 19, wherein the action to be performed comprises an instruction to establish a certain topology.
 26. The method of claim 19, further comprising generating the instruction to group the selected media streams comprises generating each of: a description packet comprising the media associated to a termination of the media resource node; and a group instruction comprising such identifiers that are to be grouped.
 27. The method of claim 19, wherein the instruction to group selected media streams comprises an information of a kind of grouping.
 28. The method of claim 27, wherein the kind of grouping is one of the following: synchronized play out of media streams; alternative play out of media streams; or alternative play out of media streams in response to a user instruction.
 29. The method of claim 19, wherein the instructions are sent in a suite of one or a plurality of H.248.1 commands.
 30. The method of claim 19, wherein the selected media streams to be grouped comprise an original digital representation and a replica representation.
 31. The method of claim 30, wherein the replica representation is sent on request from a receiver.
 32. The method of claim 19, wherein the instruction to group the selective media streams is indicative of a purpose for the grouping.
 33. A media control node for controlling a media session involving a plurality of media streams within a communications network, the media control node comprising: processing circuitry configured to determine that selected media streams out of the plurality of media streams of a media resource node are associated to each other in a media session; a transmitter configured to transmit instructions to the media resource node instructing the media resource node to: group the selected media streams of the media session; and prepare for performing an action with respect to the selected media streams.
 34. A method for establishing a media session involving a plurality of media streams within a communications network; wherein the communications network comprises a media resource node and a media control node controlling the media resource node; the method comprising the media resource node: receiving an instruction to group selected media streams of the media session and to prepare for performing an action with respect to the selected media streams; in response to receiving the instruction: grouping of the selected media streams of the media session; and performing the action.
 35. A media resource node, comprising: a receiver configured to receive instructions from a media control node to: group the selected media streams of the media session; and prepare for performing an action with respect to the selected media streams; processing circuitry configured to: group of the selected media streams of the media session; and prepare to perform the action.
 36. A computer program product stored in a non-transitory computer readable medium for controlling a media session involving a plurality of media streams within a communications network; wherein the communications network comprises a media resource node and a media control node controlling the media resource node; the computer program product comprising software instructions which, when run on processing circuitry of a the media control node, causes media control node to: determine that selected media streams out of the plurality of media streams are associated to each other in a media session; transmit, to the media resource node, an instruction to group the selected media streams of the media session; and transmit, to the media resource node, an instruction to prepare for performing an action with respect to the selected media streams.
 37. A computer program product stored in a non-transitory computer readable medium for establishing a media session involving a plurality of media streams within a communications network; wherein the communications network comprises a media resource node and a media control node controlling the media resource node; the computer program product comprising software instructions which, when run on processing circuitry of the media resource node, causes the media resource node to: receive an instruction to group selected media streams of the media session and to prepare for performing an action with respect to the selected media streams; in response to the reception of the instruction: group of the selected media streams of the media session; and perform the action. 